If you would like to adjust how often Thunderbird or Outlook checks for new mail, you can follow the steps below.
Outlook 2010+
Click on File in the Ribbon interface.
Click on Options.
When the Options screen opens, make sure you are on the Advanced tab by clicking on it.
Under the Send and Receive category (you may need to scroll down), cli on the Send/Receive... button.
Make sure "Schedule sn automatic send/received every _____ minutes." is checked, then adjust the minutes by typing a number into the box next to "minutes" or by clicking on the up or down arrow in that same box.
Click Close to close the send/receive options window, then click OK to close the Outlook options window.
Thunderbird
Click on the Tools menu and select Account Settings.
Click on the Server Settings tab.
The mail checking frequency is set with Check for new messages every __ minutes.
Click OK to save changes.
